Dichotomius (Luederwaldtius) Arias-Buriticá, 2025

Dichotomius (Luederwaldtius) Arias-Buriticá & Vaz-de-Mello, new subgenus

Type species: Copris semiaeneus Germar, 1823 View in CoL , present designation.

Etymology: The new subgenus is named after Hermann Luederwaldt (1865–1934), a German entomologist who contributed to the taxonomy of many groups of the Scarabaeoidea , especially that of the genus Dichotomius . Furthermore, in his work “As espécies brasileiras do genero Pinotus ” ( Luederwaldt, 1929), he erected the “Secção Semiaeneus ”, for Dichotomius s. str., mentioning that “Aqui attinentes as espécies mais simples e menores: O tronco do genero” (Here are the simplest and smallest species: The base of the genus). This section is in part taxonomically equivalent to our new subgenus.

Diagnosis: The species included in this subgenus are distinguished from other subgenera of Dichotomius by the following combination of characters: Head margin at the end of the fronto-clypeal sulcus with an invagination giving the appearance of being divided ( Fig. 4a, c, e View Figure 4 ). Metaventrite lacking pilosity (if present, clypeus not distinctly bidentate apically) ( Fig. 4b, d View Figure 4 ). Small to medium size (less than 20 mm).

Description: Small size to medium size (less than 20 mm) ( Fig. 4 View Figure 4 ). Body shiny or dull black, dark blue or dull green, copper. Clypeus smooth to distinctly bidentate ( Fig. 4a, c View Figure 4 ). Head with processes located in the fronto-clypeal region, simple, conical to lamellate or tridentate in males, conical to tridentate in females. Lateral margin of the head at clypeo-genal junction with division (invagination giving the appearance of being divided), and lacking angulation ( Fig. 4a, c, e View Figure 4 ). Pronotum without pronotal processes at most with a depression on the anterior area (except in males of Dichotomius camposeabrai , which have a strong central excavation) ( Fig. 4a, c View Figure 4 ). Metaventrite without pilosity (if present, clypeus not distinctly bidentate) ( Fig. 4b, d View Figure 4 ). Protibial spur slightly to abruptly angle downward near the apex ( Fig. 4f View Figure 4 ) (in D. subaeneus , bifurcate). Elytral striae well-defined and bicarenate, with small foveate punctures, shallowly impressed and spaced by two to three times their diameter ( Fig. 4a, c View Figure 4 ). Meso- and metalegs with basitarsus from subquadrangular to quadrangular. Pygidium either completely marginated or without margin at the apex. Parameres subtriangular in lateral view and with subgenital plate in ventral view ( Fig. 4 View Figure 4 g-i). ME large and subquadrangular with two well sclerotized processes on the right lateral side, the surface covered with bristles along its entire length, and on the left side it presents a membranous process with long bristles ( Fig. 4 View Figure 4 l-m) (Arias-Buriticá and Vaz-de-Mello (2012, 2019)). Colombia to central Argentina.

Composition: Dichotomius alutaceus ( Felsche 1901) , D. anthrax ( Felsche, 1901) , D. australis ( Luederwaldt, 1931b) , D. camposeabrai Martinez,1974 , D.comarapensis Génier,2000 , D.crenatipennis (Blanchard, 1846) , D. luctuosioides ( Luederwaldt, 1922) ; D. nemoricola ( Pereira, 1942a) , D. punctatostriatus ( Felsche, 1901) , D.puncticollis ( Luederwaldt, 1935) , D. semiaeneus ( Germar, 1823) , D. texanus ( Felsche, 1901) , D. virescens ( Luederwaldt, 1935) , D. belus ( Harold, 1880) , D. fornicatus ( Luederwaldt, 1931b) , D. rafanunezi Montoya-Molina & Vaz-de-Mello, 2021 , and D. subaeneus (Castelnau, 1840) (the last four previously in the subgenus Selenocopris ), and some undescribed species, the revision of this subgenus is underway (Arias-Buriticá and Vaz-de-Mello in prep.)